In the United States, shoe size is measured in inches. The measurement used is the length of the foot from the tip of the longest toe to the back of the heel. In the United States, women's shoe sizes range from 4 to 16, while men's shoe sizes range from 6 to 20.
European shoe sizes are measured in centimetres. The measurement starts at the same place as US sizes, but the value in centimeters starts at zero and adds 1.6 cm for each size. To convert from US sizes to European sizes, you can use the following formula: "European shoe size = (US shoe size - 1)/2 + 30" The result is the closest corresponding European shoe size. For example, a US women's size 7 would be a European size 38, and a US men's size 10 would be a European size 43.
Here is a table comparing shoe sizes in US, UK and European sizes:
| US Men | US Women | UK | European |
|-------|---------|---|---|
| 6 | 4 | 5.5 | 38 |
| 7 | 5 | 6.5 | 39 |
| 8 | 6 | 7.5 | 40 |
| 9 | 7 | 8.5 | 41 |
| 10 | 8 | 9.5 | 42 |
| 11 | 9 | 10.5 | 43 |
| 12 | 10 | 11.5 | 44 |
| 13 | 11 | 12.5 | 45 |
| 14 | 12 | 13.5 | 46 |
| 15 | 13 | 14.5 | 47 |
| 16 | 14 | 15.5 | 48 |
| 17 | 15 | 16.5 | 49 |
| 18 | 16 | 17.5 | 50 |
| 19 | 17 | 18.5 | 51 |
| 20 | 18 | 19.5 | 52 |
It's important to note that shoe sizes can vary between different brands and styles, so it's always a good idea to try on shoes before purchasing to ensure that they fit properly. Additionally, shoe size can also change over time, so it's recommended to have your feet measured regularly to ensure that you're wearing the correct size.